Tuneable electrical properties of hafnium aluminate gate dielectrics deposited by metal organic chemical vapour deposition

Hafnium aluminate (HfAlO) high-k films deposited by Metal Organic Chemical Vapour Deposition (MOCVD) with various Al concentrations were investigated. The results of electrical measurements show the feasibility of adjusting the relative dielectric constant of the layers in a wide range (9–16), when the aluminium concentration varies between 4% and 38%. The minimum leakage current occurs for Al concentrations up to 9%. The thinner films show Poole–Frenkel-like conduction at low field and Fowler–Nordheim-like conduction at moderate/high field, even at higher concentrations of Al into the film, while thicker films show a higher hysteresis due to an increased number of slow trapping centres in the film.